I've seen this done in race cars and BMWs before. Also, I've seen the lines run from the crank case to a catch can and then to the check valve/exhaust. That way whatever oil you do suck out of the crank case, collects in the catch can via gravity but you still have vacuum. The trick is to mount the lines to/from the catch can high on the can. Then just make sure to empty it before it fills up enough to go into the exhaust. Also cleans up your exhaust a bit since you're sucking less oil through it.
